1. Field of the Invention
This invention relates to a device for handling an object such as a pipe or pile, comprising a cylindrical member acting thereon.
2. Discussion of the Prior Art
Dutch patent application No. 7806603, laid out for public inspection describes such a device, which is particularly intended to be used when constructing offshore platforms using telescoping pipes. It comprises a cylindrical hoisting body which is to be lowered into the pipe and carries a number of sidewise extending locking elements cooperating with lugs on the inner surface of the pipe. This known structure is very complicated and costly; it is only capable of handling a limited weight and its practical use gives rise to many problems.
French Patent Specification No. 1,188,167 describes a device for lifting tubes comprising outwardly movable hooks, which fit into a corresponding ringshaped recess in the inner wall of the tube. The mechanism for actuating the hooks is based on the principle of using a cylindrical body provided with a pattern of grooves which is moved up and down to rotate it stepwise and which actuates the hooks through a cam mechanism.
Another device for lifting pipes is disclosed in U.S. Pat. No. 3,485,388; it comprises radially extensible shoes which are pressed outwardly by a conical cam in its upper position; the cam movement is controlled by means of radially extending lugs cooperating with a pattern of grooves in a cylindrical actuating mechanism which is moved up and down.
Devices comprising lugs cooperating with a pattern of grooves such as the one used in the device according to the present invention and used for actuating gripper mechanisms are known in various embodiments; examples are disclosed in the U.S. Pat. No. 1,506,827, GB Patent Specification No. 629,367, French Patent Specification No. 985,576 and U.S. Pat. No. 2,818,443.